Electric calling device



'oct. 18, 1927. 1,645,563

A. W. WHISTLECROFT ELECTRIC CALLING DEVICE Filed June 12; 1922.

I awuentoz A.W. HISTLECROFT Patented Oct. 18, 1927.

UNITED STATES PATENT OFFICE.

ARTHUR WILLIAM WHISTLECROFT, OF LONDON, ENGLAND, ASSIGNOR T RADIO COR- PORATION OF AMERICA, A CORPORATION OF DELAWARE.

ELECTRIC CALLING DEVICE.

Application filed June 12, 1922, Serial No. 567,544, and in Great Britain June 13, 1921.

This invention relates to electric calling or alarm devices adapted to ive an audible or visible call or alarm on t e receipt of a predetermined number of impulses, for ina stance a predetermined number of wireless signals of a given duration.

Alarm apparatus constructed in accordance with the invention comprises means for preventing impulses shorter than the ID predetermined callin signals from affecting the rest of the mec anlsm and means for storing up the first of the calling signals until the required number has been received, whereupon the alarm is given, so that should Hi the sequence of calling signals be interrupted, for instance, by jamming signals, the effect of these first signals may not be lost but that the alarm ma be given so soon as the predetermined num er of calling sigmale has been received.

Preferably means are also provided for preventing impulses longer than the given duration from affecting the storing mechanism.

My invention is illustrated by the accompanying drawings in which Fig. 1 is a side elevation of the apparatus involved in carrying out the invention herein described; Fig. 2 is a detail showing .the clutch operatin the contacts and associated mechanism; ig. 3 is a detailed view of the safety magnet and associated parts.

A overnor mechanism driven by anv suitable source of power such as a clockwork 8| motor ma be constructed for example on the well known principle of an ordinary gramophone governor in which a driven spindle b carries two collars c and d, one of which 0 is fixed to the'spindle and the 40 other d is free to slide thereon and carries a friction disk (1,; the two collars are connected by flat springs e or pivoted double links carrying weights f either at the junction of the links or midway in the length of I the springs. When the overnor is revolved these weights tend to y outward by centrifugal force, thus causing the free collar (1 to slide along the spindle.

Signals received by the wireless receiver are caused to actuate a relay, the secondary contacts of which close a circuit to energize 'an electromagnet g, hereinafter called the Morse magnet, which may be polarized if it is desired to have amore sensitive and 56 quicker acting magnet. The armature g of this magnet is attached to a spring influenced bar it pivoted near its middle. Normally the end of the bar remote from the armature rests on the friction plate (I, so preventing the shaft 6 from running. On the receipt of a signal the Morse magnet g is energized and the end of the bar it leaves the plate al The clockwork then commences to run. It will be understood that with ordinary Morse signals the lift of the bar It is so quick that the governor does not have time to run up to speed but just slips round slightly at each lift. The clockwork therefore is not quickly run down. On the arrival, however, of a calling signal, the duration of which should be considerably greater than that of any ordinary signal, the governor gains speed and the friction'collar d rises. After the collar (1 has risen a short distance, say, for instance, in half a second, a contact 7' is closed by an arm ja actuated by the collar. The contact closes a circuit to energize a second magnet is called the clutch magnet. A rotating wheel Z (attached for example to onebf the slow running spindles of the motor mechanism) has a soft iron rim la, see Figs. 1 and 2, and coaxial with this wheel is a soft iron spindle m free to move in centres. This spindle runs with clearance through the middle of the clutch magnet is. The spindle carries a pivoted or sprmgy extension 172 which is approximately at right angles to its axis and reaches out to the rim la but normally does not touch it. If the clutch magnet is is energized the spindle m and extension m, will be magnetized and be attracted to the now rotating rim la and revolve with it against the action of a returning spring n. The spindle m also carries another right angle extension 0 to act as a contact arm which, when it has travelled through a certain angle, makes contact with a flat spring 1) (see Figure 2). The time interval between the energizing of the Morse magnet g and the closing of this contact 0 p is the minimum length of the operating signal. This cont-act 0 p closes the circuit of a third magnet 9 (see Figure 1) called the cocking magnet. Should the signal be over length the contact arm 0 will still carry on with the wheel Z and close another contact 1' (Figure 2) to operate a fourth magnet s (Figure 1) called the tripping magnet, magnet 9 being all the while still energized. When the cocking magnet g is energized a pawl t is pulled forward over a sector it cut with ratchet teeth. The sector it is not moved on this forward stroke, but will be moved one tooth if the pawl t is allowed to return to its normal position whilst engaging with the sector a. This will bring the final contact '0 which operates the alarm bell one step forward. The sector it is retained in this position by a detent to which is also under the control of an electromagnet w. The receipt of a second calling signal causes the sector to be moved another tooth and so on. It now, as aforementioned, the signal is over length and the tripping magnet s is energized, the pawl 15 is thrown out of engagement with the sector u and the cocking magnet armature and is allowed to return harmlessly to normal without registering a tooth. The same contact that operates the tripping magnet also energizes a fifth magnet 3 (see Figures 1 and 3) called the safety magnet which attracts an armature 2 and allows a bar at to rise and close a contact 2b for a sixth magnet 20 (Figure 1) which immediately energizes and brings a clamping stop 2d down on to the friction plate d, instantly stopping the motor. This is to prevent signals of very long duration from making the clockwork run down. This contact remains made by a step on the bar so preventing the armature z from returning until the signal ceases, when the return of the bar it knocks the catch down by an arm ha and frees the stopping magnet. It will be understood that immediately the motor is stopped the clutch magnet is ceases to be energized and the contact arm 0 flies back to its stop 0 (Figure 2). It is also readily understood that if the signal had been under length the cooking magnet g would not have energized as the contact bar 0 would not have reached the contact ;0. When the requisite number of correct length signals have been registered, in this case four, the contact a comes against contact a, (Figure 1) and starts an alarm signal. The same contact ener izes the clearing magnet 40 which lifts the etent w from the sector u and allows it to be reset to zero under the action of a spring in.

It will beseen that the effect of calling impulses is stored up irrespective of the intervals between their arrival so that if a distant station sends out a number of cailing signals the alarm will be actuated so soon as the predetermined number has been received, even though there may have been, owing to jamming signals gaps in the sequence.

' This apparatus possesses the advantage that there are no parts in motion and no magnets except the magnet first receiving the impulse are energized when signals are not coming in so that unnecessary wear is obviated.

Having described my invention what I claim is:

1 In a calling device adapted to be operated by a given number of signals of a given length, the combination of means for preventing signals shorter than a pre-determined length from afl'ecting the said calling device, means for storing up the calling signals until the required number has been received, means for giving an alarm upon the receipt of the required number of calling signals, and means for preventing signals longer than the pie-determined length from affecting the storing mechanism.

2. In a calling device adapted to be operated by signals, the combination of a centrifugal governor, means for rotating it, a brake, means actuated by the receipt of a signal for releasing the brake, an electromagnet whose energizing circuit is controlled by the governor, and means for givin an alarm when said circuit has been comp eted for a given number of predetermined intervals of time.

3. In a call indicator, the combination of means responsive to signals, with a translating element arranged to be set into operation by received signals, a second translating element, means operated at a predetermined speed of said first named translating element to set said second translating element into operation, a pair of contacts andmeans controlled by said second translating element for causing relative step by step movement of said contacts to closed position.

4. In a call indicator, the combination of means responsive to signals, with a translating element arranged to be set into opera tion by received signals, a second trans lating element, means operated at a predetermined speed of said first named translating element to set said second translating element into operation, a air of contacts arranged to be moved to c osed position in a plurality of steps and means associated with said second translating element for causing relative step by step movement of said contacts.

5. In a call indicator, the combination of means responsive to signals, with a trans lating element arranged'to be set into opera tion by received signals, a second translating element, means operated at a predetermined speed of said first named translating element to set said secondtranslating element into operation, a pair of signal operating contacts and means for causing single step relative movement of said contacts toward closed position upon predetermined travel of said second translating element.

6. Ina cailiindicator, the combination means responsive to signals, With a translating element arranged to be set into operation by said responsive means, a second translating element, means operated at a predetermined speed of said first named translating element to set said second translating element into operation, a pair of signal operating-contacts, means for preparing for single step relative movement of said contacts toward closed position upon predetermined travel of said.second translating element, and means operated upon predetermined additional travel of said second translating element to prevent such travel of said contacts.

7. In a call indicator, the combination of means responsive to signals, with a translating element arranged to be set into operation by received signals, a second translating element, means operated at a predetermined speed of said first named translating element to set said second translating element into operation, a pair of signal operating contacts, a pair of contacts and means controlled by said second translating element to cause relative step by step movement of said contacts toward closed position, and means responsive toduration of received impulses for positively preventing operation of said first translating element.

8. In a call indicator, the combination of element to set said second translating ele- 1 ment into operation, a pair of contacts arranged to be carried by relative step by step movement toward closed position, means for normally retaining said contacts in position, means operative in response to signals of predetermined duration for preparing such contacts for single step movement and means responsive to predetermined additional duration of received impulses for resetting said preparing means to initial position.

9. In a call selector, the combination of a pair of contacts arranged for relative step by step movement toward closed position, means for normally maintaining the space relation of said contacts, means for preparing said contacts for single step movement when the duration of received impulses exceeds a predetermined minimum value, and means for resetting said preparing means to initial position Without actuation of said contacts when the duration of received impulses exceeds a predetermined maximum value.

ARTHUR- WILLIAM WHISTLECROFT. 

